Transflective liquid crystal display device and fabricating method thereof

ABSTRACT

A transflective liquid crystal display device includes a pixel region having reflective and transmissive portions. A first passivation layer having one or more protrusions in the reflective portion is disposed on a thin film transistor formed on a first substrate. A reflective layer disposed on the first passivation layer in the reflective portion is uneven, at least in part due to the protrusions. A second passivation layer and a pixel electrode are disposed on the first passivation layer. A color filter layer disposed on an inner surface of the second substrate has at least one through hole in the reflective portion. An overcoat layer disposed on the color filter layer has an open portion in the transmissive portion. A common electrode is disposed on the overcoat layer and a liquid crystal layer is disposed between the pixel electrode and the common electrode.

[0001] The present invention claims the benefit of Korean PatentApplication No. 2003-32871, filed in Korea on May 23, 2003, which ishereby incorporated by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a liquid crystal display device,and more particularly, to a transflective liquid crystal display deviceand a fabricating method thereof.

[0004] 2. Discussion of the Related Art

[0005] Flat panel display (FPD) devices having portability and low powerconsumption have been a subject of increasing research in the presentinformation age. Generally, FPD devices may be classified according totheir ability for self-emission, and may include emissive displaydevices and non-emissive display devices. The emissive display devicesdisplay images by taking advantage of their ability to self-emit light,and the non-emissive display devices require a light source since theydo not emit light by themselves. For example, plasma display panel (PDP)devices, field emission display (FED) devices, and electroluminescentdisplay (ELD) devices are commonly used as emissive display devices.Liquid crystal display (LCD) devices may be categorized as non-emissivedisplay devices and are commonly used in notebook and desktop computersbecause of their high resolution, capability of displaying coloredimages, and high quality image display.

[0006] In general, an LCD device includes two substrates disposed suchthat respective electrodes of the two substrates face into each other. Aliquid crystal layer is interposed between the respective electrodes.When a voltage is applied to the electrodes, an electric field isgenerated and the electric field modulates the light transmittance ofthe liquid crystal layer by reorienting liquid crystal molecules,thereby displaying images in the LCD device.

[0007] Since the LCD device is a non-emissive-type display device, anadditional light source is required. Thus, a backlight unit is disposedunder an LCD panel, wherein the LCD device displays images using lightproduced by the backlight unit. The respective electrodes of the twosubstrates of the LCD device may be formed of a transparent conductivematerial and the two substrates of an LCD device may be formed of atransparent material. The above-mentioned LCD device is referred to as atransmissive type LCD device. Even though the transmissive type LCDdevice displays bright images under dark surroundings due to anartificial light source such as a backlight unit, power consumption ofthe LCD device increases due to the backlight unit.

[0008] In order to improve above disadvantages of the transmissive typeLCD device, a reflective type LCD device has been suggested. Since thereflective type LCD device uses the ambient artificial or natural lightinstead of light from the backlight unit, power consumption of thereflective type LCD device is smaller than that of the transmissive typeLCD device. In the reflective LCD device, a reflective layer of ametallic material having a high reflectance is formed on a firstsubstrate and a common electrode of a transparent conductive material isformed on a second substrate. Even though the low power consumption ofthe reflective type LCD device is improved, the reflective type LCDdevice may not be used where the ambient light is weak or does not existdue to low brightness.

[0009] In order to overcome such problems, a transflective LCD devicehas been researched and developed. The transflective LCD device can beswitched from a transmissive mode using transmission of light to areflective mode using reflection of light according to the user'sselection. Accordingly, disadvantages of the transmissive type LCDdevice and the reflective type LCD device such as high power consumptionand low brightness under dark surroundings are improved.

[0010]FIG. 1 is a schematic cross-sectional view of a transflectiveliquid crystal display device having a single cell gap according to therelated art.

[0011] In FIG. 1, a gate electrode 6 is formed on a first substrate 2and a gate insulating layer 10 is formed on the gate electrode 6. Eventhough not shown in FIG. 1, a gate line connected to the gate electrode6 is formed under the gate insulating layer 10. An active layer 13 andan ohmic contact layer 16 a and 16 b are sequentially formed on the gateinsulating layer 10 over the gate electrode 6. Source and drainelectrodes 23 and 26 are formed on the ohmic contact layer 16 a and 16b. The source and drain electrodes 23 and 26 constitute a thin filmtransistor (TFT) “Tr” with the gate electrode.

[0012] A data line 20 of the same material as the source and drainelectrodes 23 and 26 is formed on the gate insulating layer 10. Eventhough not shown in FIG. 1, the data line 20 is connected to the sourceelectrode 23. The data line 20 crosses the gate line (not shown) todefine a pixel region “SP.” A first passivation layer 30 of an organicmaterial having a low dielectric constant is formed on the TFT “Tr.” Areflective layer 40 of a metallic material having a high reflectance isformed on the first passivation layer 30 in a reflective portion “RA.”The reflective layer 40 has an open portion 40 a corresponding to atransmissive portion “TA.” A second passivation layer 45 of an inorganicmaterial is formed on the reflective layer 40. A pixel electrode 50connected to the drain electrode 26 through a contact hole 55 is formedon the second passivation layer 45 in each pixel region “SP.”

[0013] A black matrix 75 is formed on a second substrate 71 and a colorfilter layer 80 including red, green and blue sub-color filters 80 a, 80b and 80 c is formed on the black matrix 75. An overcoat layer 85 and acommon electrode 90 of a transparent conductive material aresequentially formed on the color filter layer 80. One sub-color filter80 a, 80 b and 80 c corresponds to one pixel electrode 50. The blackmatrix 75 overlaps edge of the pixel electrode 50 and corresponds to thedata line 20.

[0014] A liquid crystal layer 60 is formed between the pixel electrode50 and the common electrode 90. When a voltage is applied to the pixelelectrode 50 and the common electrode 90, arrangement state of liquidcrystal molecules in the liquid crystal layer 60 changes according to anelectric field generated between the pixel electrode 50 and the commonelectrode 90. Even though not shown in FIG. 1, respective orientationfilms are formed on the pixel electrode 50 and the common electrode 90to determine an initial arrangement state of the liquid crystalmolecules. Respective retardation films 97 and 95 are formed outsides ofthe first and second substrates 2 and 71 to adjust phase of light.

[0015] In the transflective LCD device of FIG. 1, a first cell gap “d₁”of the reflective portion “RA” is similar to a second cell gap “d₂” ofthe transmissive portion “TA.” Accordingly, cell efficiency between thereflective portion “RA” and transmissive portion “TA” is not optimized.These cause problems such as reduction of transmittance and brightness.To overcome above problems, a transflective LCD device having a dualcell gap is suggested.

[0016]FIG. 2 is a schematic cross-sectional view of a transflectiveliquid crystal display device having a dual cell gap according to therelated art. Illustration for the same portions as the transflective LCDdevice of FIG. 1 will be omitted.

[0017] In FIG. 2, a first passivation layer 30 has an open portion 30 acorresponding to a transmissive portion “TA.” Accordingly, a first cellgap “d₃” of the reflective portion “RA” is a half of a second cell gap“d₄” of the transmissive portion “TA.” A liquid crystal layer 60includes liquid crystal molecules of an electrically controlledbirefringence (ECB) mode. When liquid crystal molecules of an ECB modeare used for an LCD device, transmittance curve of the LCD device hasperiodic peaks every multiple of a unit cell gap. Accordingly, lightefficiency in the reflective portion “RA” is similar to that in thetransmissive portion “TA” and cell efficiency of the reflective portion“RA” and the transmissive portion “TA” is maximized.

[0018] The reflective LCD devices of FIGS. 1 and 2, however, haveproblems such that color property is reduced in the transmissiveportion. While light passes through the color filter layer twice, i.e.,before and after reflection in the reflective portion, light from thebacklight unit passes the color filter layer once in the transmissiveportion. Accordingly, light emitted from the transmissive portion isdifferent from that from the reflective portion in color property.Moreover, reflection efficiency is not maximized due to flatness of thereflective layer. Recently, to overcome the above problems, atransflective LCD device has been suggested that incorporates a colorfilter layer with a through hole and an uneven reflective layer.

[0019]FIG. 3 is a schematic cross-sectional view of a transflectiveliquid crystal display device having a dual cell gap, a color filterlayer including a through hole and a reflective layer having unevennessaccording to the related art. Illustration for the same portions as thetransflective LCD devices of FIGS. 1 and 2 will be omitted.

[0020] In FIG. 3, a color filter layer 80 including red, green and bluesub-color filters 80 a, 80 b and 80 c has a through hole “TH” to adjustcolor property and brightness. The through hole “TH” does not includecolor resin for the color filter layer 80, and color property andbrightness may be adjusted by varying number and size of the throughhole “TH.” Since the through hole “TH” corresponds to a reflectiveportion “RA,” color property and brightness of light emitted from thereflective portion “RA” becomes similar to those of light emitted from atransmissive portion “TA.” Moreover, since a reflective layer 41includes unevenness, reflection efficiency is improved.

[0021] First and second passivation layers 30 and 31 are sequentiallyformed on a thin film transistor (TFT) “Tr.” The first passivation layer30 has a protrusion 32 for unevenness of the reflective layer 41 and anopen portion 30 a for a dual cell gap such that a first cell gap “d₃” inthe transmissive portion “TA” is a double of a second cell gap “d₄” inthe reflective portion “RA.” The protrusion 32 and the open portion 30 amay be formed through one etching process. However, it is hard to obtainan optimum process condition for the protrusion 32 and the open portion30 a simultaneously. Moreover, the optimum process condition for theprotrusion 32 and the open portion 30 a may be changed according to thenumber and the size of the through hole “TH” of the color filter layer80. Accordingly, design and fabricating process for the transflectiveLCD device are not stable, and inferiority may occur during thefabricating process.

SUMMARY OF THE INVENTION

[0022] Accordingly, the present invention provides a liquid crystaldisplay device that substantially obviates one or more of the problemsdue to limitations and disadvantages of the related art.

[0023] This is to say that the present invention provides atransflective liquid crystal display device having high reflectionefficiency, high color efficiency and high brightness, and a fabricatingmethod thereof.

[0024] The present invention also provides a transflective liquidcrystal display device having a dual cell gap, a color filter layerincluding a through hole and a reflective layer including unevenness,and a fabricating method thereof.

[0025] Additional features and advantages of the invention will be setforth in the description which follows, and in part will be apparentfrom the description, or may be learned by practice of the invention.These and other advantages of the invention will be realized andattained by the structure particularly pointed out in the writtendescription and claims hereof as well as the appended drawings.

[0026] To achieve these and other advantages, as embodied and broadlydescribed, a transflective liquid crystal display device includes: firstand second substrates facing and spaced apart from each other; a gateline and a data line on an inner surface of the first substrate, thegate line and the data line crossing each other to define a pixel regionhaving reflective and transmissive portions; a thin film transistorconnected to the gate line and the data line; a first passivation layeron the thin film transistor, the first passivation layer having aprotrusion in the reflective portion; a reflective layer on the firstpassivation layer and having unevenness; a second passivation layer onthe reflective layer; a pixel electrode on the second passivation layer;a color filter layer on an inner surface of the second substrate, thecolor filter layer having at least one through hole in the reflectiveportion; an overcoat layer on the color filter layer, the overcoat layerhaving an open portion in the transmissive portion; a common electrodeon the overcoat layer; and a liquid crystal layer between the pixelelectrode and the common electrode.

[0027] In another aspect, a transflective liquid crystal display deviceincludes: first and second substrates facing and spaced apart from eachother; a gate line and a data line on an inner surface of the firstsubstrate, the gate line and the data line crossing each other to definea pixel region having reflective and transmissive portions; a thin filmtransistor connected to the gate line and the data line; a firstpassivation layer on the thin film transistor, the first passivationlayer having a protrusion in the reflective portion; a pixel electrodeon the first passivation layer; a reflective layer on the pixelelectrode and having unevenness; a color filter layer on an innersurface of the second substrate, the color filter layer having at leastone through hole in the reflective portion; an overcoat layer on thecolor filter layer, the overcoat layer having an open portion in thetransmissive portion; a common electrode on the overcoat layer; and aliquid crystal layer between the pixel electrode and the commonelectrode.

[0028] In another aspect, a fabricating method of an array substrate fora transflective liquid crystal display device includes: forming a gateline and a data line on a substrate, the gate line and the data linecrossing each other to define a pixel region having reflective andtransmissive portions; forming a thin film transistor connected to thegate line and the data line; forming a first passivation layer on thethin film transistor, the first passivation layer having a protrusion inthe reflective portion; forming a reflective layer on the firstpassivation layer and having unevenness; forming a second passivationlayer on the reflective layer; and forming a pixel electrode on thesecond passivation layer.

[0029] In another aspect, a fabricating method of an array substrate fora transflective liquid crystal display device includes: forming a gateline and a data line on a substrate, the gate line and the data linecrossing each other to define a pixel region having reflective andtransmissive portions; forming a thin film transistor connected to thegate line and the data line; forming a first passivation layer on thethin film transistor, the first passivation layer having a protrusion inthe reflective portion; forming a pixel electrode on the firstpassivation layer; and forming a reflective layer on the pixel electrodeand having unevenness.

[0030] In another aspect, a fabricating method of a color filtersubstrate for a transflective liquid crystal display device includes:forming a color filter layer on a substrate having reflective andtransmissive portions, the color filter layer having at least onethrough hole in the reflective portion; forming an overcoat layer on thecolor filter layer, the color filter layer having an open portion in thetransmissive portion; and forming a common electrode on the overcoatlayer.

[0031] It is to be understood that both the foregoing generaldescription and the following detailed description are exemplary andexplanatory and are intended to provide further explanation of theinvention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The accompanying drawings, which are included to provide afurther understanding of the invention and are incorporated in andconstitute a part of this specification, illustrate embodiments of theinvention and together with the description serve to explain theprinciples of the invention. In the drawings:

[0033]FIG. 1 is a schematic cross-sectional view of a transflectiveliquid crystal display device having a single cell gap according to therelated art;

[0034]FIG. 2 is a schematic cross-sectional view of a transflectiveliquid crystal display device having a dual cell gap according to therelated art;

[0035]FIG. 3 is a schematic cross-sectional view of a transflectiveliquid crystal display device having a dual cell gap, a color filterlayer including a through hole and a reflective layer having unevennessaccording to the related art;

[0036]FIG. 4 is a schematic plane view of a transflective liquid crystaldisplay device according to a first embodiment of the present invention;

[0037]FIG. 5 is a schematic cross-sectional view taken along a line“V-V” of FIG. 4;

[0038]FIG. 6 is a schematic cross-sectional view of a transflectiveliquid crystal display device according to a second embodiment of thepresent invention;

[0039]FIGS. 7A to 7G are schematic cross-sectional views showing afabricating process of an array substrate for a liquid crystal displaydevice according to a first embodiment of the present invention;

[0040]FIGS. 8A to 8E are schematic cross-sectional view showing afabricating process of an array substrate for a liquid crystal displaydevice according to a second embodiment of the present invention; and

[0041]FIGS. 9A to 9D are schematic cross-sectional views showing afabricating process of a color filter substrate for a liquid crystaldisplay device according to a first embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0042] Reference will now be made in detail to the preferred embodimentsof the present invention, an example of which is illustrated in theaccompanying drawings.

[0043]FIG. 4 is a schematic plane view of a transflective liquid crystaldisplay device according to a first embodiment of the present invention.

[0044] In FIG. 4, a gate line 103 and a data line 120 cross each otherto define a pixel region “SP” and a thin film transistor (TFT) “Tr” isconnected to the gate line 103 and the data line 120. A color filterlayer of a color resin includes red, green and blue sub-color filterssequentially disposed in the pixel region “SP.” The pixel region “SP”includes a transmissive portion “TA” and a reflective portion “RA.” Thecolor filter layer has a through hole “TH” in the reflective portion“RA.” The through hole “TH” may be formed by removing the color resin.

[0045]FIG. 5 is a schematic cross-sectional view taken along a line“V-V” of FIG. 4.

[0046] In FIG. 5, a gate electrode 106 and a gate line (not shown) areformed on a first substrate 101. A gate insulating layer 110 of aninorganic material such as silicon oxide (SiO₂) and silicon nitride(SiNx) is formed on the gate electrode 106 and the gate line (notshown). An active layer 113 of amorphous silicon and an ohmic contactlayer 116 a and 116 b of impurity-doped amorphous silicon aresequentially formed on the gate insulating layer 110 over the gateelectrode 106. Source and drain electrodes 123 and 126 are formed on theohmic contact layer 116 a and 116 b. The gate electrode 106, the activelayer 113, the ohmic contact layer 116 a and 116 b, the source electrode123 and the drain electrode 126 constitute a thin film transistor (TFT)“Tr” of a switching element. A data line 120 of the same material as thesource and drain electrodes 123 and 126 is formed on the gate insulatinglayer 110. Even though not shown in FIG. 5, the data line 120 isconnected to the source electrode 123 and the data line 120 crosses thegate line to define a pixel region “SP” including a transmissive portion“TA” and a reflective portion “RA.”

[0047] First and second passivation layers 130 and 131 of an organicmaterial such as benzocyclobutene (BCB) and acrylic resin aresequentially formed on the data line 120 and the source and drainelectrodes 123 and 126. The first passivation layer 130 has one or moreprotrusions 132 in the reflective portion “RA” to obtain unevenness of areflective layer 140. The second passivation layer 131 has an unevensurface in the reflective portion “RA” due to the protrusion 132 of thefirst passivation layer 130. A reflective layer 140 of a metallicmaterial is formed on the second passivation layer 131 in the reflectiveportion “RA.” The reflective layer 140 has unevenness on its surface dueto the uneven surface of the second passivation layer 131. A thirdpassivation layer 145 of an inorganic material such as silicon oxide(SiO₂) and silicon nitride (SiNx) is formed on the reflective layer 140.The third passivation layer 145 has a drain contact hole 155 exposingthe drain electrode 126 through the reflective layer 140, the secondpassivation layer 131 and the first passivation layer 130. A pixelelectrode 150 of a transparent conductive material such asindium-tin-oxide (ITO) and indium-zinc-oxide (IZO) is formed on thethird passivation layer 145 in the pixel region “SP.” The pixelelectrode 150 is connected to the drain electrode 126 through the draincontact hole 155.

[0048] A black matrix 175 of one of a metallic material and a resin isformed on a second substrate 171. The black matrix 175 corresponds tothe gate line (not shown) and the data line 120. A color filter layer180 including red, green and blue sub-color filters 180 a, 180 b and 180c is formed on the black matrix 175. Each of red, green and bluesub-color filters 180 a, 180 b and 180 c corresponds to the pixel region“SP.” The color filter layer 180 has a through hole “TH” in thereflective portion “RA.” The color filter layer 180 may be formed ofcolor resin and the through hole “TH” may be formed by removing thecolor resin. An overcoat layer 185 of a transparent material is formedon the color filter layer 180. The overcoat layer 185 has an openportion 185 a in the transmissive portion “TR.” In other words, theovercoat layer 185 is present in the reflective portion but essentiallynot in the transmissive portion. In addition, the overcoat layer 185fills the through hole “TH.” A common electrode 190 is formed on theovercoat layer 185.

[0049] A liquid crystal layer 160 is formed between the pixel electrode150 and the common electrode 190. A first cell gap (i.e., a thickness ofthe liquid crystal layer 160) “d₅” in the reflective portion “RA” may beformed to be substantially a half of a second cell gap “d₆” in thetransmissive portion “TA” by adjusting a height of the overcoat layer185 in the reflective portion “RA.” Accordingly, a cell efficiency ofthe reflective portion “RA” and the transmissive portion “TA” ismaximized. Moreover, since a color filter layer 180 has a through hole“TH” in the reflective portion “RA,” a uniform color property andbrightness of the reflective portion “RA” and the transmissive portion“TA” may be obtained. In addition, since the reflective layer 140includes unevenness, reflection efficiency may be improved.

[0050] In the LCD device according to the second embodiment of thepresent invention, a dual cell gap for the maximum cell efficiency maybe obtained by adjusting the height of an overcoat layer 185 on a secondsubstrate 171. Therefore, problems occurring when a protrusion forunevenness and an open portion for a dual cell gap are simultaneouslyformed on a first substrate through one etching process are solved.

[0051]FIG. 6 is a schematic cross-sectional view of a transflectiveliquid crystal display device according to a second embodiment of thepresent invention.

[0052] In FIG. 6, a gate electrode 206 and a gate line (not shown) areformed on a first substrate 201. A gate insulating layer 210 of aninorganic material such as silicon oxide (SiO₂) and silicon nitride(SiNx) is formed on the gate electrode 206 and the gate line (notshown). An active layer 213 of amorphous silicon and an ohmic contactlayer 116 a and 116 b of impurity-doped amorphous silicon aresequentially formed on the gate insulating layer 210 over the gateelectrode 206. Source and drain electrodes 223 and 226 are formed on theohmic contact layer 216 a and 216 b. The gate electrode 206, the activelayer 213, the ohmic contact layer 216 a and 216 b, the source electrode223 and the drain electrode 226 constitute a thin film transistor (TFT)“Tr” as a switching element. A data line 220 of the same material as thesource and drain electrodes 223 and 225 is formed on the gate insulatinglayer 210. Even though not shown in FIG. 6, the data line 220 isconnected to the source electrode 223 and the data line 220 crosses thegate line (not shown) to define a pixel region “SP” including atransmissive portion “TA” and a reflective portion “RA.”

[0053] First and second passivation layers 230 and 231 of an organicmaterial such as benzocyclobutene (BCB) and acrylic resin aresequentially formed on the data line 220 and the source and drainelectrodes 223 and 226. The first passivation layer 230 has a protrusion232 in the reflective portion “RA” to obtain unevenness of a reflectivelayer 240. The second passivation layer 231 has an uneven surface in thereflective portion “RA” due to the protrusion 232 of the firstpassivation layer 230. The first and second passivation layers 230 and231 have a drain contact hole 255 exposing the drain electrode 226.

[0054] A pixel electrode 250 of a transparent conductive material suchas indium-tin-oxide (ITO) and indium-zinc-oxide (IZO) is formed on thesecond passivation layer 231 in the pixel region “SP.” The pixelelectrode 250 is connected to the drain electrode 226 through the draincontact hole 255. The pixel electrode 250 has an uneven surface in thereflective portion “RA” due to the protrusion of the first passivationlayer 230. A reflective layer 240 of a metallic material such asaluminum (Al) and aluminum (Al) alloy is formed on the pixel electrode250 in the reflective portion “RA.” Since the reflective layer 240directly contacts the pixel electrode 250, the reflective layer 240 hasunevenness on its surface due to the uneven surface of the pixelelectrode 250.

[0055] A liquid crystal layer 260 is formed between the reflectiveelectrode 240 and a common electrode 290. A first cell gap (i.e., athickness of the liquid crystal layer 260) “d₇” in the reflectiveportion “RA” may be formed to be substantially a half of a second cellgap “d₈” in the transmissive portion “TA” by adjusting a height of anovercoat layer 285 in the reflective portion “RA.” Accordingly, a cellefficiency of the reflective portion “RA” and the transmissive portion“TA” is maximized. Moreover, since a color filter layer 280 has athrough hole “TH” in the reflective portion “RA,” a uniform colorproperty and brightness of the reflective portion “RA” and thetransmissive portion “TA” may be obtained. In addition, since thereflective layer 240 includes unevenness, reflection efficiency may beimproved.

[0056] As in the first embodiment, a black matrix 275 of a metallicmaterial or resin is formed on the second substrate 271. The blackmatrix 275 corresponds to the gate line (not shown) and the data line220. The color filter layer 280 that includes red, green and bluesub-color filters 280 a, 280 b and 280 c is formed on the black matrix275. Each of red, green and blue sub-color filters 280 a, 280 b and 280c corresponds to the pixel region “SP.” The overcoat layer 285 is formedof a transparent material on the color filter layer 280, has an openportion 285 a in the transmissive portion “TR,” and fills the throughhole “TH.” A common electrode 290 is formed on the overcoat layer 285.

[0057] In the LCD device according to the second embodiment of thepresent invention, a dual cell gap for the maximum cell efficiency maybe obtained by adjusting the height of an overcoat layer 285 on a secondsubstrate 271. Therefore, problems occurring when a protrusion forunevenness and an open portion for a dual cell gap are simultaneouslyformed on a first substrate through one etching process are solved.

[0058]FIGS. 7A to 7G are schematic cross-sectional views showing afabricating process of an array substrate for a liquid crystal displaydevice according to a first embodiment of the present invention.

[0059] In FIG. 7A, a gate electrode 106 and a gate line (not shown) areformed on a substrate 101 by depositing and patterning a metallicmaterial such as chromium (Cr), aluminum (Al) and copper (Cu). Thedeposited metallic material may be patterned through a photolithographicprocess using a photoresist (PR). The gate electrode 106 and the gateline (not shown) may have a double layer of aluminum/molybdenum (Al/Mo).A gate insulating layer 110 is formed on the gate electrode 106 and thegate line (not shown) by depositing an inorganic material such assilicon oxide (SiO₂) and silicon nitride (SiNx).

[0060] In FIG. 7B, an active layer 113 and an ohmic contact layer 116 aand 116 b are sequentially formed on the gate insulating layer 110 overthe gate electrode 106 by depositing and patterning amorphous siliconand impurity-doped amorphous silicon. Source and drain electrodes 123and 126 are formed on the ohmic contact layer 116 a and 116 b bydepositing a metallic material such as chromium (Cr), molybdenum (Mo)and aluminum (Al). The source and drain electrodes 123 and 126 arespaced apart from the gate electrode 106 disposed therebetween. At thesame time, a data line 120 crossing the gate line (not shown) to definea pixel region “SP” is formed on the gate insulating layer 110. The dataline 120, the source electrode 123 and the drain electrode 126 may beformed of a double layer such as aluminum/chromium (Al/Cr) andaluminum/molybdenum (Al/Mo). A portion (not shown) of the ohmic contactlayer exposed between the source and drain electrodes 123 and 126 isremoved by using the source and drain electrodes 123 and 126 as anetching mask and the active layer 113 is exposed between the source anddrain electrodes 123 and 126. The gate electrode 106, the active layer113, the ohmic contact layer 116 a and 116 b, the source electrode 123and the drain electrode 126 constitute a thin film transistor (TFT) “Tr”as a switching element. Even though not shown in FIG. 7B, the data line120 is connected to the source electrode 123.

[0061] In FIG. 7C, a first passivation layer 130 is formed on the dataline 120 and the source and drain electrodes 123 and 126 by coating anorganic material such as benzocyclobutene (BCB) and acrylic resin. Thefirst passivation layer 130 has a first protrusion 132 a in a reflectiveportion “RA” of the pixel region “SP.” For example, when BCB is used forthe first passivation layer 130, a photoresist (PR) pattern (not shown)may be formed on the first passivation layer 130 and the firstpassivation layer 130 may be patterned using the PR pattern as a mask toobtain the first protrusion 132 a. When photo-acryl is used as acrylicresin for the first passivation layer 130, the first protrusion 132 amay be obtained by exposure and development of the photo-acryl withoutusing PR. Negative type photo-acryl or positive type photo-acryl may beused for the first passivation layer 130. For illustration, photo-acrylis used for the first passivation layer 130 in FIG. 7C. The firstprotrusion 132 a may have a trapezoid shape and a slant angle of thefirst protrusion 132 a may be adjusted using a space between patterns ofa photo mask for the first protrusion 132 a.

[0062] In FIG. 7D, the first protrusion 132 a may become a secondprotrusion 132 of a round shape through heat treatment. The firstprotrusion 132 a may be melted and flow. Then, the melted firstprotrusion 132 a is solidified to be the second protrusion 132.

[0063] In FIG. 7E, a second passivation layer 131 is formed on the firstpassivation layer 132 by depositing and baking an organic material suchas benzocyclobutene (BCB) and acrylic resin. The second passivationlayer 131 has an uneven surface in the reflective portion “RA” due tothe second protrusion 132 of the first passivation layer 130.

[0064] In FIG. 7F, a reflective layer 140 is formed on the secondpassivation layer 131 in the reflective portion “RA” by depositing andpatterning a metallic material having a high reflectance such asaluminum (Al) and aluminum (Al) alloy. The reflective layer 140 hasunevenness due to the uneven surface of the second passivation layer131. The reflective layer 140 is not formed on or removed from areasthat correspond to a transmissive portion “TA” and a drain contact holeportion 140 a for exposing the drain electrode 126. When the metallicmaterial is deposited directly on the second passivation layer 131 of anorganic material through sputtering method, the metallic material maycontaminate interior of a chamber. Since the contamination of thechamber can cause inferiority in a subsequent process, an additionalinsulating layer (not shown) of an inorganic material may be formed onthe second passivation layer 131 before forming the reflective layer140.

[0065] In FIG. 7G, a third passivation layer 145 is formed on thereflective layer 140 by depositing one of an inorganic material such assilicon oxide (SiO₂) and silicon nitride (SiNx) or coating an organicmaterial such as benzocyclobutene (BCB) and acrylic resin. Then, a draincontact hole 155 exposing the drain electrode 126 is formed by etchingthird passivation layer 145, the second passivation layer 131 and thefirst passivation layer 130. A pixel electrode 150 is formed on thethird passivation layer 145 in the pixel region “SP” by depositing andpatterning a transparent conductive material such as indium-tin-oxide(ITO) and indium-zinc-oxide (IZO). The pixel electrode 150 is connectedto the drain electrode 126 through the drain contact hole 155.

[0066]FIGS. 8A to 8E are schematic cross-sectional view showing afabricating process of an array substrate for a liquid crystal displaydevice according to a second embodiment of the present invention.

[0067] In FIG. 8A, a gate electrode 206 and a gate line (not shown) areformed on a substrate 201. A gate insulating layer 210 is formed on thegate electrode 206 and the gate line (not shown) by depositing aninorganic material such as silicon oxide (SiO₂) and silicon nitride(SiNx). An active layer 213 and an ohmic contact layer 216 a and 216 bare sequentially formed on the gate insulating layer 210 over the gateelectrode 206 by depositing amorphous silicon and impurity-dopedamorphous silicon and patterning amorphous silicon and impurity-dopedamorphous silicon. Source and drain electrodes 223 and 226 are formed onthe ohmic contact layer 216 a and 216 b. At the same time, a data line220 is formed on the gate insulating layer 210. The gate electrode 206,the active layer 213, the ohmic contact layer 216 a and 216 b, thesource electrode 223 and the drain electrode 226 constitute a thin filmtransistor (TFT) “Tr” as a switching element. Even though not shown inFIG. 8A, the data line 220 is connected to the source electrode 223 andthe data line 220 crosses the gate line (not shown) to define a pixelregion “SP.”

[0068] First passivation layer 230 is formed on the data line 220 andthe source and drain electrodes 223 and 226 by coating an organicmaterial such as benzocyclobutene (BCB) and acrylic resin. In a secondembodiment, for example, BCB is used for the first passivation layer230. After coating BCB, a photoresist PR layer 233 a is coated on thefirst passivation layer 230. A mask 235 having a transmissive region anda shielding region is disposed over the PR layer 233 a and light isirradiated onto the PR layer 233 a through the mask 235.

[0069] In FIG. 8B, a PR pattern 233 corresponding to the reflectiveportion “RA” is obtained by developing the irradiated PR layer 233 a (ofFIG. 8A). The first passivation layer 230 is etched using the PR pattern233 as an etch mask.

[0070] In FIG. 8C, a protrusion 232 corresponding to the PR pattern 233(of FIG. 8B) is obtained by etching the first passivation layer 230. Asecond passivation layer 231 is formed on the first passivation layer230 by coating an organic material such as benzocyclobutene (BCB) andacrylic resin. The second passivation layer 231 has an uneven surface inthe reflective portion “RA” due to the protrusion 232 of the firstpassivation layer 230.

[0071] In FIG. 8D, a drain contact hole 255 exposing the drain electrode226 is formed by etching the first and second passivation layers 230 and231. A pixel electrode 250 connected to the drain electrode 226 throughthe drain contact hole 255 is formed on the second passivation layer 231by depositing and patterning a transparent conductive material such asindium-tin-oxide (ITO) and indium-zinc-oxide (IZO). The pixel electrode250 has an uneven surface in the reflective portion “RA” due to theprotrusion 232 of the first passivation layer 230.

[0072] In FIG. 8E, a reflective layer 240 is formed on the pixelelectrode 250 in the reflective portion “RA” by depositing andpatterning a metallic material having high reflectance. Since thereflective layer 240 directly contacts the pixel electrode 250, thereflective layer 240 has unevenness on its surface due to the unevensurface of the pixel electrode 250 and the reflective layer 240functions as an electrode.

[0073]FIGS. 9A to 9D are schematic cross-sectional views showing afabricating process of a color filter substrate for a liquid crystaldisplay device according to a first embodiment of the present invention.

[0074] In FIG. 9A, a black matrix 175 is formed on a substrate 171 bydepositing and patterning a metallic material or coating and patterninga resin. The black matrix 175 may be omitted in an LCD device of highresolution and high aperture ratio.

[0075] In FIG. 9B, a red sub-color filter 180 a having a through hole“TH” in the reflective portion “RA” is formed on the black matrix 175 bycoating and patterning red color resin. The number and size of thethrough hole “TH” may be determined according to color property of thereflective portion “RA” and the transmissive portion “TA.”

[0076] In FIG. 9C, green and blue sub-color filters 180 b and 180 chaving a through hole “TH” in the reflective portion “RA” aresequentially formed on the black matrix 175 through a process similar tothat for the red sub-color filter 180 a. Even though not shown in FIG.9C, the red, green and blue sub-color filters 180 a, 180 b and 180 ccorresponding a pixel region “SP” alternate with each other through thesubstrate 171 and constitute a color filter layer 180.

[0077] In FIG. 9D, an overcoat layer 185 is formed on the color filterlayer 180 by coating and patterning a transparent material. The overcoatlayer 185 has an open portion 185 a in the transmissive portion “TR” andexposing the color filter layer 180. The overcoat layer 185 may beformed to have a thickness in the reflective portion “RA” substantiallya half of a cell gap (not shown) of an LCD in the transmissive portion“TA.” In addition, the overcoat layer 185 fills the through hole “TH.” Acommon electrode 190 is formed on the overcoat layer 185 by depositingone of indium-tin-oxide (ITO) and indium-zinc-oxide (IZO).

[0078] The array substrate fabricated through a process of FIGS. 7A to7F or FIGS. 8A to 8E and the color filter substrate fabricated through aprocess of FIGS. 9A to 9C may be attached through a cell processincluding an orientation step, a gap step and an inspection step, and aliquid crystal layer may be formed between the pixel electrode and thecommon electrode.

[0079] Consequently, a liquid crystal display device according to thepresent invention has some advantages. Since a reflective layer includesunevenness, reflection efficiency may be improved. A passivation layerhaving a protrusion for the unevenness of the reflective layer is formedwithout step generation between reflective and transmissive portions.Accordingly, process problems occurring when the protrusion and the stepare simultaneously formed through one etching process are solved andinferiority in fabrication is reduced. Even though the step between thereflective and transmissive portions is not formed in the passivationlayer on an array substrate, the step is formed in an overcoat layer ona color filter substrate. Accordingly, a dual cell gap is obtained and acell efficiency of the reflective and transmissive portions ismaximized. Moreover, since a color filter layer has a plurality ofthrough holes in the reflective portion, uniform color property and highbrightness of the reflective and transmissive portions are obtained byadjusting total number and unit size of the through holes.

What is claimed is:
 1. A transflective liquid crystal display device,comprising: first and second substrates facing and spaced apart fromeach other; a gate line and a data line on an inner surface of the firstsubstrate, the gate line and the data line crossing each other to definea pixel region having reflective and transmissive portions; a thin filmtransistor connected to the gate line and the data line; a firstpassivation layer on the thin film transistor, the first passivationlayer having at least one protrusion in the reflective portion; anuneven reflective layer on the first passivation layer in the reflectiveportion, the unevenness of the reflective layer at least in part due tothe at least one protrusion under the reflective layer; a pixelelectrode on the first passivation layer; a color filter layer on aninner surface of the second substrate, the color filter layer having atleast one through hole in the reflective portion; an overcoat layer onthe color filter layer, the overcoat layer having an open portion in thetransmissive portion; a common electrode on the overcoat layer; and aliquid crystal layer between the pixel electrode and the commonelectrode.
 2. The device according to claim 1, further comprising asecond passivation layer disposed on the reflective layer, wherein thepixel electrode is disposed on the second passivation layer.
 3. Thedevice according to claim 1, wherein the reflective layer is disposed onthe pixel electrode.
 4. The device according to claim 1, furthercomprising a black matrix between the second substrate and the colorfilter layer.
 5. The device according to claim 1, wherein a thickness ofthe overcoat layer between the common electrode and portions of thecolor filter layer in which the at least one through hole is not presentis substantially the same as that of the liquid crystal layer in thereflective portion.
 6. The device according to claim 1, wherein athickness of the liquid crystal layer between the common electrode andportions of the color filter layer in which the at least one throughhole is not present in the reflective portion is substantially a half ofthat in the transmissive portion.
 7. The device according to claim 6,wherein at least a portion of the increase in the thickness of theliquid crystal layer in the transmissive portion compared with thethickness of the liquid crystal layer in the reflective portion is dueto a decrease in a thickness of the overcoat layer between thetransmissive and reflective portions.
 8. The device according to claim7, wherein substantially the entire increase in the thickness of theliquid crystal layer is due to the decrease in the thickness of theovercoat layer.
 9. The device according to claim 8, wherein the entireincrease in the thickness of the liquid crystal layer is due to thedecrease in the thickness of the overcoat layer and absence of thereflective layer.
 10. The device according to claim 1, wherein athickness of the first passivation layer in the transmissive portion issubstantially the same as the thickness of the first passivation layerin a section of the reflective portion in which the transistor isabsent.
 11. The device according to claim 1, wherein the firstpassivation layer is present in the transmissive portion.
 12. The deviceaccording to claim 11, wherein the first passivation layer does notcontain any protrusions in the transmissive portion.
 13. The deviceaccording to claim 1, further comprising a third passivation layerbetween the first passivation layer and the reflective layer, the thirdpassivation layer having an uneven surface due at least in part to theat least one protrusion.
 14. The device according to claim 1, furthercomprising an insulating layer of an inorganic material between thefirst passivation layer and the reflective layer.
 15. The deviceaccording to claim 1, wherein the pixel electrode is connected to thethin film transistor.
 16. The device according to claim 1, wherein thecolor filter layer includes red, green and blue sub-color filters. 17.The device according to claim 1, further comprising a second passivationlayer between the first passivation layer and the pixel electrode, thesecond passivation layer having an uneven surface due at least in partto the at least one protrusion.
 18. A fabricating method of an arraysubstrate for a transflective liquid crystal display device, comprising:forming a gate line and a data line on a substrate, the gate line andthe data line crossing each other to define a pixel region havingreflective and transmissive portions; forming a thin film transistorconnected to the gate line and the data line; forming a firstpassivation layer on the thin film transistor, the first passivationlayer having at least one protrusion in the reflective portion; formingan uneven reflective layer on the first passivation layer in thereflective portion that has unevenness at least in part due to the atleast one protrusion; and forming a pixel electrode on the firstpassivation layer.
 19. The method according to claim 18, furthercomprising forming a second passivation layer on the reflective layerand the pixel electrode on the second passivation layer.
 20. The methodaccording to claim 18, further comprising forming the reflective layeron the pixel electrode.
 21. The method according to claim 18, whereinthe reflective layer includes one of aluminum and aluminum alloy. 22.The method according to claim 18, further comprising forming aninsulating layer of an inorganic material between the first passivationlayer and the reflective layer.
 23. The method according to claim 18,wherein the first passivation layer includes one of benzocyclobutene andacrylic resin.
 24. The method according to claim 18, wherein the secondpassivation layer includes one of silicon oxide and silicon nitride. 25.The method according to claim 18, wherein the second passivation layerincludes one of benzocyclobutene and acrylic resin.
 26. The methodaccording to claim 19, further comprising forming a contact hole throughthe first and second passivation layers and connecting the pixelelectrode to the thin film transistor through the contact hole.
 27. Themethod according to claim 18, further comprising providing a liquidcrystal layer in the transmissive and reflective portions and increasinga thickness of the liquid crystal layer in the transmissive portioncompared with the thickness of the liquid crystal layer in thereflective portion without decreasing a thickness of any other layer onthe substrate besides the reflective layer.
 28. The method according toclaim 18, further comprising substantially maintaining a thickness ofthe first passivation layer between the transmissive portion and asection of the reflective portion in which the transistor is absent. 29.The method according to claim 18, further comprising forming the firstpassivation layer in the transmissive portion.
 30. The method accordingto claim 29, further comprising forming the first passivation layer inthe transmissive portion such that no protrusions are formed in thetransmissive portion.
 31. A fabricating method of a color filtersubstrate for a transflective liquid crystal display device, comprising:forming a color filter layer on a substrate having reflective andtransmissive portions, the color filter layer having at least onethrough hole in the reflective portion; forming an overcoat layer on thecolor filter layer, the color filter layer having an open portion in thetransmissive portion; and forming a common electrode on the overcoatlayer.
 32. The method according to claim 31, wherein the overcoat layerincludes photo-acryl of a negative type.
 33. The method according toclaim 31, further comprising providing a liquid crystal layer on thecommon electrode, wherein a thickness of the overcoat layer between thecommon electrode and portions of the color filter layer in which the atleast one through hole is not present is substantially the same as thatof the liquid crystal layer in the reflective portion.
 34. The methodaccording to claim 31, further comprising providing a liquid crystallayer in the transmissive and reflective portions and increasing athickness of the liquid crystal layer in the transmissive portioncompared with the thickness of the liquid crystal layer in thereflective portion by decreasing a thickness of the overcoat layer. 35.The method according to claim 31, wherein forming the color filter layercomprises: coating a red color resin on the substrate; patterning thered color resin to form a red sub-color filter having the through holein the reflective portion; coating a green color resin on the substrate;patterning the green color resin to form a green sub-color filter havingthe through hole in the reflective portion; coating a blue color resinon the substrate; and patterning the blue color resin to form a bluesub-color filter having the through hole in the reflective portion.